The present invention relates generally to methods of and apparatus for ultrasonically removing material, and more particularly, toward a highly efficient and versatile ultrasonic probe as well as methods of using the probe for descaling the teeth and pulverizing cataract tissue.
Dental and surgical procedures involving the use of an ultrasonic probe for removing tissue are well known. For example, in dentistry, various ultrasonic probes having operative tips that are caused to vibrate at a frequency of about 30,000 Hz with a stroke of about 1 mil are applied to the teeth and vibrated to remove scale and plaque from tooth surfaces. A tip of the probe which is formed of a thin, hollow titanium tube, besides cutting away the scale and plaque during vibration, also serves as an irrigation conduit. A fluid is caused to flow through the tip by gravity to produce a flushing action from the tip as the vibrating tip removes plaque and scale formations. A wide variety of special interchangeable tips are generally provided for removing various types of accretions from the tooth surfaces in different regions of the mouth.
One object of the present invention, therefore, is to provide a new and improved ultrasonic probe for removing dental scale and plaque from tooth surfaces.
In the past, in opthalmological surgery, cataract removal has been commonly undertaken using standard intracapular cataract extraction techniques which, although generally satisfactory, require a prolonged recovery time of up to several months. Recently, a procedure known as phaco-emulsification, or use of an ultrasonic probe to break up and remove cataracts, has become widely used because it offers a remarkable decrease in recovery time; a patient can sometimes return to work the day after surgery. In accordance with this procedure for removal of cataract tissue, as described in the article entitled "History of Emulsification And Aspiration of Senile Cataracts," by Charles D. Kelman, appearing in Transaction of the American Academy of Opthalmology and Otoaryngology, Volume 78, January-February, 1974, pages OP5-13 (originally presented at the 78th Annual Meeting of the American Academy of Ophthalmology and Otoaryngology, Dallas, Tex., Sept. 16-20, 1973), a tip in the form of a hollow tube is inserted into the anterior chamber of the eye through a small incision into contact with the cataract tissue. The tip is vibrated by a hand held probe at an ultrasonic rate, and hydrodynamic flow of a special solution is established in order to prevent collapse of the anterior chamber. As particles of the cataract tissue are cut from the cataract mass, the particles are removed from the chamber through the tip of the ultrasonic probe. In the case of hard cataracts, these particles, which have a tendency to slide into contact with the walls of the chamber, have an abrasive character. Certain portions of the eye are more prone to abrasion sensitivity. Accordingly, the cataract particles must be completely drained from the anterior chamber without contacting the chamber walls.
During aspiration of cataract tissue, the tip of the ultrasonic probe must be very carefully manipulated under the field of view of a microscope in order to prevent aspirating other than cataract tissue. Close control of the tip is especially critical at the peripheral regions of the cataract.
Accordingly, one object of the invention is to provide a new and improved probe for ultrasonically removing tissue.
Another object of the invention is to provide a new and improved ultrasonic probe for performing phaco-emulsification for cataract removal.
Still another object of the invention is to provide a new and improved probe and method for performing cataract removal using phaco-emulsification wherein cataract particles are completely drained from the anterior chamber to avoid damage to delicate eye tissue, and an operative tip is precisely controlled in the peripheral as well as central regions of the cataract.
In prior art devices of which I am aware, substantial energy loss in caused by poor coupling between the piezoelectric crystals and operative tip of the hand held probe. The reason for poor coupling is that the crystals are positioned within a housing so as to extend along only a small portion of the operative tip of the probe, and the vibrational energy applied to the tip has difficulty overcoming the mass of the tip body.
The housing of the probe is typically of unitary construction. Occasionally, the probe must be serviced to correct electrical or mechanical breakdowns. It is difficult to gain access into the housing, and once in, the individual elements of the probe, e.g., piezoelectric crystals, cannot be readily disassembled.
Furthermore, several different tips are generally used during a surgical procedure, such as dental descaling or phaco-emulsification. These tips must be quickly interchanged during each procedure. Binding up of the tips within the housing frequently occurs in ultrasonic probes of the type described, and this slows down the surgical procedure.
Accordingly, an additional object of the invention is to provide a new and improved ultrasonic probe having improved energy transfer efficiency to the operative tip.
Another object of the invention is to provide a new and improved ultrasonic probe that is easy to dissemble and service, as needed.
Still another object of the invention is to provide a new and improved ultrasonic probe, wherein the operative tips thereof are readily interchangeable.